Diamines serve as building blocks for a wide range of polymers such as polyamides, polyimides, and polyureas, enabling the creation of materials with tunable properties from flexible to rigid, suitable for various applications including additive manufacturing. Currently, most diamines are manufactured through chemical refining processes that rely on fossil-based resources. Microbes can be genetically engineered to produce diverse diamines from renewable sources. However, their efficiency and productivity remain insufficient for large-scale industrial applications. The key technical challenge is the slow design-build-test-learn (DBTL) cycle of microbial biocatalyst development. Evaluating diamine-producing microbes typically involves time-consuming sample preparation and high-performance liquid chromatography (HPLC) analysis. There is a critical need to develop a high-throughput assay enabling threshold-based diamine detection, useful for microbial strain development. Without such a screening method, sustainable biomanufacturing for diverse diamines including 1,5-diaminopentane (DAP) will likely remain challenging and costly. To address the challenge, we developed a nanofabricated DAP sensor and high-throughput screening method using the sensor. We first established a nanofabrication process for reproducible and reliable nano-gap structure. Then, the nanostructure was charged with a diamine specific chemical linker synthesized through click chemistry. The prototype DAP sensor was successfully applied to combinatorial engineering of Escherichia coli whole-cell biocatalyst producing DAP. The nano-gap sensor can be tailored for the detection of various energy chemicals such as alcohols and ketones, potentially powerful for accelerating synthetic biology for biofuels, chemicals, and materials production.
